[SOLVED] Rearranging a differential equation

Hi I am supposed to "just" rearrange the following equation and at one point substitute dh/dt = A/rho with the constant A:

http://www.texify.com/img/%5CLARGE%5...7D%7Bdh%7D.gif

With the constant C and rho(i).

The result looks like this:

http://www.texify.com/img/%5CLARGE%5...-%5Crho%29.gif

I cannot rearrange the 1st equation in a way that I obtain the 2nd. I assume that one has to ibntegrate at one point to get rid of the logarithm though.

Thanks in advance.

Cheers